How to switch antidepressants safely

Several years ago, I was prescribed the antidepressant citalopram for generalised anxiety disorder. As I expected, the first few weeks were rough - I felt nauseous and foggy, and I had constant headaches. I thought the side effects would dissipate over time, but unfortunately they didn't. Months later, I felt as anxious as I did before and my brain felt like it was stuffed with cotton wool, making it difficult to focus on anything.

I spoke to my doctor, who suggested switching to another type of SSRI (selective serotonin reuptake inhibitor) called sertraline. We worked out a plan to taper off the old medication gradually and introduce the new one, to avoid me feeling worse in the interim. However, I still experienced a plethora of miserable symptoms, from nausea and fatigue to 'brain zaps' - mini electric shock-like sensations in the brain.

After some time, though, my body began to adjust to the new drugs and I began to feel better. The side effects wore off and my anxiety began to feel more manageable. Had I switched medications more suddenly, my unpleasant symptoms may have been much worse.

"There is a large body of evidence for the effectiveness of antidepressant medication in people with moderate to severe depressive disorder," says Dr Natasha Bijlani, a consultant psychiatrist at Priory Hospital Roehampton. "These drugs can have a valuable role to play in the management of moderate to severe anxiety disorders, alongside psychological interventions such as cognitive behavioural therapy."

However, not everyone finds the right antidepressant for them on the first attempt. For me, it took changing medications to finally get my anxiety under control - a gradual but worthwhile process.

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How to change antidepressants safely

Switching antidepressants should only be carried out under the advice and guidance of an experienced doctor who is aware of your history and any co-existing medical problems. It's also important for your doctor to know about any allergies or other medications you are taking, to avoid interactions.

It's essential to keep taking your medication unless your doctor says otherwise - and to follow their plan for switching drugs. Stopping your current medication too quickly can lead to withdrawal symptoms, or can cause the symptoms of your mental health issue to return.

"If a patient needs to change from one antidepressant to another, abrupt withdrawal should usually be avoided," says Bijlani.

Cross-tapering

"A method termed 'cross-tapering' is generally advisable," says Bijlani. "This is when the dose of the drug which has been deemed ineffective or poorly tolerated is slowly reduced, while the new drug is gradually introduced. In the case of some medications, cross-tapering must be avoided because of the risk of serious adverse effects with combination use."

Direct switch

Depending on the type of medication you are taking, it may be possible to stop taking your current drug and start on a new antidepressant the next day. However, this can depend on whether you are going from an SSRI or SNRI (serotonin-norepinephrine reuptake inhibitor) to another drug in the same class.

Reduce and switch

"With some drugs, one could gradually reduce the dose of the first antidepressant and then start the second antidepressant immediately after discontinuation of the first," says Bijlani.

Taper, washout and switch

"Sometimes tapering the first drug until it is stopped, then switching to the second antidepressant after waiting for a few days, is recommended. The interval between use of one antidepressant and another is termed the 'washout' period," adds Bijlani.

The washout period can be a few days or weeks, depending on the medication you were originally taking and how long it takes to leave your system fully. This approach can help to prevent the two drugs from interacting and may be recommended if you are changing from one class of antidepressants to another.

How your doctor will choose the right strategy

When it comes to changing your medication, the approach your doctor will choose will depend on various different factors. They will take into consideration the severity of your symptoms, as it may not be safe for you to come off antidepressants for days or weeks.

It can also depend on your current medication and which drugs you are switching between. Certain antidepressants can interact with each other in dangerous ways. For example, it is inadvisable for clomipramine - a type of tricyclic antidepressant - to be cross-tapered with the SSRIs paroxetine and fluvoxamine.

Your doctor will check guidance such as that from the National Institute for Health and Care Excellence (NICE) to confirm which strategy to take.

Why switching antidepressants is a delicate process

Crucially, the process of changing antidepressants should be done with care, under the supervision of your doctor. This will help to avoid side effects and the worsening of the symptoms of depression and anxiety.

Another risk of switching antidepressants is serotonin syndrome, a potentially serious condition that can occur if you start taking a new medication before the old one is out of your system. It is an excess of serotonin in the body, which can cause a range of symptoms from agitation and confusion to high blood pressure and seizures.

"Switching antidepressants should only be done by individuals following medical guidance," says Bijlani, "People should have regular reviews as well as the opportunity to communicate with their doctor about any problems they might be experiencing during the process."